1. Field of the Invention
The present invention relates to rupturable fluid pressure relief apparatus and methods of manufacturing such apparatus, and more particularly, but not by way of limitation, to improved rupturable fluid pressure relief apparatus capable of rupturing in either the normal or reverse rupture modes.
2. Description of the Prior Art
A variety of rupturable pressure relief apparatus have been developed and used heretofore. Generally, these devices include a rupture disk supported betweem a pair of complementary support members or flanges which are in turn connected to a relief connection in a vessel or system containing fluid pressure. When the fluid pressure within the vessel or system exceeds the design rupture pressure of the rupture disk, rupture occurs allowing fluid pressure to be relieved from the vessel or system. The term "rupture pressure" is used herein to mean the fluid pressure or fluid pressure differential exerted on or across the rupture disk which causes the rupture disk to rupture.
Most of the rupturable pressure relief apparatus of the prior art is designed for failure in one direction. That is, the apparatus is installed in a pressurized system between first and second pressure zones, so that when excess pressure occurs in the first zone, it is vented to the second zone. This is referred to as the "normal rupture mode".
In some applications of rupturable pressure relief apparatus it is not only necessary that the apparatus relieve fluid pressure in the normal rupture mode, i.e., from the first zone to the second zone, but also that the apparatus relieve fluid pressure in the reverse direction, i.e., from the second zone to the first zone. This is referred to as the "reverse rupture mode".
Heretofore, rupturable pressure relief apparatus have been developed and utilized which relieve pressure in both the normal and reverse rupture modes. For example, U.S. Pat. Nos. 3,091,359 to Wood and 4,301,938 to Wood et al. are directed to safety pressure relief devices which can relieve fluid pressure in either direction. However, these devices as well as rupturable fluid pressure relief apparatus designed to rupture in the normal rupture mode only are caused to rupture at a predetermined rupture pressure by the configuration, thickness and the type of material or materials utilized to form the rupture disk or one or more rupturable members in the devices. That is, the prior art rupturable fluid pressure relief apparatus are all generally designed to open fully upon rupture and the size of the rupturable member or members of the apparatus and the fluid flow passageway provided by the support members are as large as possible depending upon the nominal size of the apparatus. In order to produce rupturable fluid pressure relief apparatus of the same nominal size having different predetermined rupture pressures, the strength of the rupturable member or members has heretofore been changed to change the rupture pressure, i.e., the changing of the strength of the rupturable member or members has been accomplished by changing the material from which the rupturable member or members are formed, changing the thickness of the material utilized, changing the configuration of the rupturable member or members whereby they are weakened, etc. This requires the manufacturer to have on hand a great variety of materials and a variety of tooling which in turn causes the manufacturing process of prior art rupturable pressure relief apparatus to be costly.
By the present invention an improved rupturable fluid pressure relief apparatus and method of manufacturing such apparatus are provided wherein rupture disks of the same configuration, material and thickness are utilized in support members of the same nominal size, but the rupture pressures of the rupture disks are selectively differed by including different rupture pressure control members in the apparatus. That is, the particular normal and reverse rupture mode rupture pressures of individual apparatus are set by annular rupture pressure control members having centrally positioned openings therein of sizes less than the sizes of the openings in the support members positioned on opposite sides of the rupture disk. The particular size of the openings in the control members determines the particular normal and reverse rupture pressures which cause the rupture of the rupture disk.
Thus, by the present invention identical rupture disks, i.e., rupture disks of the same material, thickness, etc., can be utilized in identical support members to form apparatus having a variety of normal and reverse rupture mode rupture pressures thereby substantially reducing the manufacturing costs of the apparatus.